Thank you all very much for your help. :-) However, how could I tell if a process is possible for on-shell particles? So... picking a simple process a photon annihilating to give an electron and positron. How can I determine if this is possible for on-shell particles?
Cheers, Samantha
This is right. The reason it's a trace is because the definition of the trace is the sum of all the diagonal elements, Tr A = Sum A_{ii} (Sorry, I don't know how to get Latex stuff on here!). So, you have the same index at the start and the end of your T-matrix element, that's why it's a trace...
What do we mean when we say "on shell" particles?
Hello!
What do we mean when we say a particle in on shell? What is off shell? I gather it is related to energy and momentum conservation to say if a process is possible, but I've no idea what it actually is. Is it something to do with...
Hello! I'm afraid I've asked this before, a while ago, but I still don't completely understand. It's not a homework question as such, but I thought this might be an appropriate place to put it.
Homework Statement
Why is it that pions decay via pi^+ --> mu^+ + antimuon neutrino 98% of...
Hello!
I was wondering if someone could help me with a problem of units!
I'm currently deriving probability equations for neutrino oscillations and I'm stuck with units!
I have: [(mass)^2 * time]/[4*energy] and I want to write it as [1.27 * (mass)^2 * distance]/[Energy] with distance in...
Hello! I was just wondering something...
Why is it that a negative pion always decays into a muon and antimuon neutrino? Why not an electron and antielectron neutrino? (and the same for a positive pion)
Any answers would be grately appreciated :-)
Samantha
Hello! I hope I've posted this in the correct section...
I'm a 3rd year undergraduate and we're currently studying Vector Spaces (in QM) and I just don't understand what injective (one-to-one) and surjective (onto) mean? As a result I have no idea what an isomorphism is!
I realise this is...
Homework Statement
I have a questions on Neutrino Oscillations, but i have no idea how to solve any of it... this is just one part...
How do I show that the probability of a mu neutrino having transformed into a tau neutrino at a time t is:
sin^2(2theta)sin^2[((difference in masses...
Hey! I am completely confused...
In quantum mechanics at University we are learning about operators. I don't understand what you actually have to do to write an operator as a matrix...
In my notes, I'm looking at the kinetic energy operator in the Hamiltonian...
I can see for something...
Is it not something to do with the fact that light does not have a wavelength small enough for us to see the spaces, as they're so small... so we have to use gamma rays ones and what not? I really have no clue... just guessing!
I have a few questions about Neutrino Oscillations...
Firstly, why are they called oscillations? Is it because they can go back and forth to different flavours/masses?
Next, if, for example, a tau neutrino is produced in the sun, will it oscillate to the other flavours on its way to earth...
Thanks!
This is where I'm getting confused though, because if the y components cancel then when I find the magnitude of the field I will just be squaring the x components, so I won't have anything to the power of a half to expand using the Binomial? :confused: